Factory 4.1 RCT System Basics

Initial Thoughts

As I’ve come to expect with FMF, the Factory 4.1 RCT Exhaust System is an amazing looking, well made product. The install is a breeze and really couldn’t be much easier – the hardest part was removing the stock system.

FMF’s Claims

FMF claims the Megabomb/4.1 RCT Technology offers

Low end to mid-range gains as well as broadening out the mid to top end power gains over stock.

Reduces sound output as much as 1.5dB

Increases output from stock motor as much as 3hp with a full system

Does this system fulfill the claims? I would say the description of the power it produces is pretty accurate. I don’t have a dyno, but I really don’t think it produces a 3hp increase on this bike. I also don’t think that it reduces the sound output. It’s pretty dang loud compared to the stocker. Maybe they’re talking about a decrease in noise with one of the rapid tuning system inserts installed?

The Power

There is a noticeable change in power characteristics when riding with the FMF 4.1 RCT system. The KTM 450 SX-F’s abrupt hit off the very bottom is smoothed out a bit (although it is still present) after that where there is a bit of a drop off in stock form, the FMF system pulls harder, making it possible to carry an extra gear in many situations.

That said I don’t feel the full system offers a huge performance performance advantage over the FMF Factory 4.1 RCT Slip-On with stock header. I would say the small noticeable difference is in the bottom end to low-mid, where the full system offers a bit more power and allows you to carry that extra gear a bit easier.

Durability

Over 30 hours of use this exhaust has held up very well. I have repacked it once, which isn’t too surprising, but other than that everything’s stayed tight, nothing has cracked, I have no complaints.

Final Thoughts

For this bike, you may as well save your money. A slip on is more cost effective, but it probably doesn’t even need that. That is, unless you are cutting weight from your bike one part at a time or just want an exhaust for cool factor, in either of those cases you should totally buy one.